In football the propensity of players to sock it to their former team is called “the immutable law of the ex.” Now, a study by researchers at the University College Dublin, finds statistically that the “law” is very real.

Outside of sports, the impact of defections by key employees is not as easy to quantify. For large organisations, great performance depends on many things, including resources at hand and specific industry challenges. But anger or a desire for revenge, be it on the field or in the office, may not be the career or workplace negative it’s long been presumed to be. Instead, it could be a key to turning in a top performance.

In a study of 402 head-to-head encounters between players and their former teams, players who left on bad terms consistently outperformed their new teammates. Whether attributed to a thirst for revenge, a keen sense of how the former team does things, or a bid to prove loyalty to the new line-up, footballers excelled when battling former teammates.

“For employees, channelling anger into superior performance can transform something traditionally seen as a negative into something beneficial,” said Karan Sonpar, co-author of the report.

Sonpar and his co-authors see implications for many fields of business where talent and relationships are crucial. Among them: investment banking, accounting and legal services, where relationships with clients are key. A few talented individuals can also make a difference in technology or advertising industries.

Sifting through 1,600 press accounts of such football matches, the researchers found certain themes repeated by media, coaches and the players themselves as explanation for their high level of play. For one, the players seemed to have a heightened desire to win against their old team. Many voiced a desire to prove their loyalty to their new employer. Knowledge of their former squad and former coach’s style was a key asset, too. Players who left on bad terms consistently outplayed their teammates, including being more likely to score a goal.

Corporate comparisons

While quantifying the effect in the corporate world may be harder, the danger posed by a skilled ex-employee isn’t any less concerning.

Of those who leave Deloitte Consulting, the firm particularly worries about employees who defect to another consulting firm, said Robin Erickson Lead Analyst for Talent Acquisition, at Bersin by Deloitte, a division of the global consulting firm.

“They take so much knowledge with them of our methods, our solutions, our client base, knowledge of the industry,” she said. “They know all the secrets.”

Some companies are fighting back. Lawsuits in the US seeking to enforce non-compete agreements have risen 61% over the past decade, according to the Wall Street Journal, and companies from computer chipmaker Advanced Micro Devices to financial services company Credit Suisse, among others, have recently sued departed executives claiming theft of trade secrets.

They have reason for concern. In business, unlike sports, defectors can end up creating new competitors. Semiconductor chip giant Intel grew to become far larger than Fairchild Semiconductor, the company where Intel founders Gordon Moore and Robert Noyce worked before launching the rival firm. German software maker SAP, now an $87 billion market cap company, one of the largest software companies in the world, started when five engineers left IBM after a project they had worked on was nixed.

In 1995 two former editors of the Harvard Business Review launched a new business magazine, Fast Company. Before leaving, one of the co-founders, Alan Webber, approached a professor at the business school who had once said he would help the pair with their endeavour. The professor declined, commenting, as Webber recalls, “Why would anyone need another business magazine when they have the Harvard Business Review?”

That motivated Webber as he spent months trying to create a new enterprise and convince the world it was worthwhile.

“With Fast Company we wanted to prove the idea was great, but I had another motivation too. ‘You want to know who else needs another business magazine? The world does and I’m going to prove it’,” he said.

“When you are trying to move a rock up a mountain, you need as much motivating energy as you can get. You need great allies but it also helps to have a good enemy, someone you want to prove things to,” Webber said.

Five years after its launch, Fast Company was sold for $350 million, the second-highest price for a magazine at the time.